Termite Biology Research Articles

Deciphering the synergism of endogenous glycoside hydrolase families 1 and 9 from Coptotermes gestroi

Termites can degrade up to 90% of the lignocellulose they ingest using a repertoire of endogenous and symbiotic degrading enzymes. Termites have been shown to secrete two main glycoside hydrolases, which are GH1 (EC 3.2.1.21) and GH9 (EC 3.2.1.4) members. However, the molecular mechanism for lignocellulose degradation by these enzymes remains poorly understood. The present study was conducted to understand the synergistic relationship between GH9 (CgEG1) and GH1 (CgBG1) from Coptotermes gestroi, which is considered the major urban pest of São Paulo State in Brazil. The goal of this work was to decipher the mode of operation of CgEG1 and CgBG1 through a comprehensive biochemical analysis and molecular docking studies. There was outstanding degree of synergy in degrading glucose polymers for the production of glucose as a result of the endo-β-1,4-glucosidase and exo-β-1,4-glucosidase degradation capability of CgEG1 in concert with the high catalytic performance of CgBG1, which rapidly converts the oligomers into glucose. Our data not only provide an increased comprehension regarding the synergistic mechanism of these two enzymes for cellulose saccharification but also give insight about the role of these two enzymes in termite biology, which can provide the foundation for the development of a number of important applied research topics, such as the control of termites as pests as well as the development of technologies for lignocellulose-to-bioproduct applications.

Teacher Characteristics and Perceptions of Pest Management Curricula: Clues to Adoption and Continuation.

Educate to Eradicate is a K-12 curriculum project using termite biology and control as the basis for science education that has been implemented in over 350 Hawaii public school classrooms. To encourage sustained implementation of the project, we aimed to identify factors that influence the adoption and continuation of pest management curricula in public school classrooms. Regression analysis of teacher survey data were used to create predictive models of teacher continuation. Teachers motivated by “exciting students about science”, who perceived increases in “student understanding and comprehension of major termite knowledge concepts” and/or students as “more interested in termites after participating in this project” were more likely to continue curriculum. Teachers who had worked at their current school over 21 years at the time of curriculum adoption, and/or who identified having subject specialties not listed on the survey were less likely to continue curriculum. Additionally, teachers servicing lower socioeconomic level students were less likely to continue the curricula.

Influence of Environmental Factors on Activity Patterns of <I>Incisitermes minor</I> (Isoptera: Kalotermitidae) in Naturally Infested Logs

Acoustic emission (AE) activity patterns were measured from seven loquat [Eriobotrya japonica (Thunb.) Lindl.] logs, five containing live western drywood termite [Incisitermes minor (Hagen)] infestations, and two without an active drywood termite infestation. AE activity, as well as temperature, were monitored every 3 min under unrestricted ambient conditions in a small wooden building, under unrestricted ambient conditions but in constant darkness, or in a temperature-controlled cabined under constant darkness. Logs with active drywood termite infestations displayed similar diurnal cycles of AE activity that closely followed temperature with a peak of AE activity late in the afternoon (1700-1800 hours). When light was excluded from the building, a circadian pattern continued and apparently was driven by temperature. When the seven logs were kept at a relatively constant temperature (approximately 23 +/- 0.9 degrees C) and constant darkness, the pattern of activity was closely correlated with temperature, even with minimal changes in temperature. Temperature is the primary driver of activity of these drywood termites, but the effects are different when temperature is increasing or decreasing. At constant temperature, AE activity was highly correlated with the number of termites in the logs. The possible implications of these findings on our understanding of drywood termite biology and how this information may affect inspections and posttreatment evaluations are discussed.

Optimizing Pest Management Curricula for Adoption in K-12 Classrooms

The Formosan subterranean termite (Coptotermes formosanus Shiraki) is the most economically important insect pest in Hawaii, costing over $100 million annually in control and repair (Tamashiro et al. 1990). The University of Hawaii Termite Project: Educate to Eradicate is a statewide program intended to suppress termites through research and education (Grace et al. 2007). This program has been developed and conducted in partnership with USDA-ARS, and is intended as a modification of more traditional agricultural “area-wide” pest management programs, using public schools to reach and influence the behavior of Hawaii residents over a large area, rather than focusing efforts exclusively on a single community or more limited geographic area. The Educate to Eradicate K-12 curricula project has been implemented in over 350 Hawaii public school classrooms on the islands of Oahu, Maui, and Hawaii, with over 12,530 students from 2001 to present. It is designed to teach children and adolescents principles of science and biology using curricula emphasizing termite biology, prevention, and control. Hawaii state science process and life science instructional standards are addressed, facilitating standards-based instruction while teaching novel termite content (HCPS III 2007). Educate to Eradicate curricula utilize live termites for observations and investigations. Students establish termite habitats that are observed over several weeks (Fig. 1). These habitats serve as the springboard for lessons on the scientific method, including data collection, predictions, and inquiry. Habitats spark class discussion of adaption, communication, and interdependence. Subsequent lessons and investigations use a range of grade-appropriate pedagogies to further explore these concepts, in addition to termite lifecycles, prevention, and control (Grace et al. 2008). Curricula incorporate both inspection of the students’ own residences for termite hazards with parent/guardian participation, and a culminating service-learning project that requires application of unit knowledge to community outreach activities. These aspects of the curricula result in knowledge transfer from participating students to homeowners within the community (Lemus et al. 2010, Schmidt et al. 2007). The goal of this project is a self-sustaining curriculum that requires limited institutional inputs, increases science literacy in Hawaii schools, and will help protect current and future homeowners from incurring structural termite damage (Mason et al. 2013a). Educate to Eradicate curricular materials, including lesson plans, PowerPoint presentations, guided notes, reinforcement worksheets, insect fact sheets, and laboratory handouts, are available for teachers on compact disk and online (http://manoa. hawaii.edu/ctahr/termite/). Partner teachers in Hawaii receive professional development, materials, laboratory supplies, and equipment needed to complete the lessons. Supplies and items supplied on a loan basis include books, puppets, craft kits, preserved insects, live termites, habitats, laptops, digital microscopes, and projectors. Curricula are differentiated for grades Kindergarten, 1, 2, 3, 4/5, middle, and high school levels. This study was initiated to flesh out factors that influence adoption and continued use of our pest management curricula in public school classrooms. Initial paperand-pencil surveys completed by partner teachers revealed trends in continuation (Mason et al. 2013b). Teacher focus groups were organized to more robustly assess Educate to Eradicate curriculum design and professional development implementation. Perceptions of key project components and supports were recorded during teacher focus groups. Our findings will inform modifications to curricula, professional development, and project supports. The goal of this assessment was to optimize our limited resources to maximize teacher continuation and student learning.

Genetic Evidence for Multiple Invasions of the Eastern Subterranean Termite Into Canada

Social insects are among the world's most successful species at invading new environments. Their characteristic division of labor can influence their capacity to colonize new habitats, often with negative ecological or economic impact. The social Hymenoptera (i.e., ants, bees, and wasps), are well studied in this regard, but much less is known about the invasive biology of termites (Isoptera). In this study we use province-wide sampling and a population genetic analysis to infer the minimum number of eastern subterranean termite [Reticulitermes flavipes (Kollar)] introductions into Ontario (Canada). Structure analysis of multilocus microsatellite genotypes grouped the 30 collection points into K = 3 genetic clusters, suggesting as many three independent introductions into southern Ontario. Levels of genetic diversity were higher in termites from the Pelee region than in termites from Toronto and other Ontario cities, suggesting that these Pelee termite populations are potentially older and native to Ontario. A single origin scenario, in which all populations stem from a single source, therefore is not supported by the genetic data. Instead, our analysis suggests multiple independent introductions of this highly social, subterranean termite into Ontario, where the species is now well established as a structural pest of urban habitats.

Kumar Krishna, in appreciation

Kumar Krishna, in appreciation

Evaluation of polyphenols-rich natural compounds as treatments to prevent attacks by subterranean and drywood termites: preliminary results

In the view to find sustainable methods to prevent termite attacks to wooden objects and structural timbers, this study represents a preliminary step in the evaluation of some natural substances considered as effective by some African popular traditions. Dark shea cake, obtained from the kernels of <em>Vitellaria paradoxa </em>(Sapotaceae), is the phase just before the extraction of shea (= karitè) butter. In some West African regions, by-products from this extraction are traditionally believed to protect houses from termites. To verify if this practice has scientific basis, shea cake was used in experiments with both subterranean and drywood termites, respectively <em>Reticulitermes lucifugus </em>(Rossi) (Rhinotermitidae) and <em>Kalotermes flavicollis </em>(Fabricius) (Kalotermitidae). As shea nuts are extremely rich in polyphenols, the trials included a comparison with tannins from chestnut (<em>Castanea sativa</em>). Short-term experiments to evaluate repellency and<em> </em>feeding deterrence of the two compounds were performed. Results showed differences in the behavior of the two termites species and that shea cake is significantly more repellent than chestnut tannins, especially for <em>K. flavicollis</em>. No feeding deterrence activity was detected for either substance for either termite species. Further investigation is currently being performed to better clarify how these compounds affect termite biology.

Multiple Levels of Synergistic Collaboration in Termite Lignocellulose Digestion

In addition to evolving eusocial lifestyles, two equally fascinating aspects of termite biology are their mutualistic relationships with gut symbionts and their use of lignocellulose as a primary nutrition source. Termites are also considered excellent model systems for studying the production of bioethanol and renewable bioenergy from 2nd generation (non-food) feedstocks. While the idea that gut symbionts are the sole contributors to termite lignocellulose digestion has remained popular and compelling, in recent years host contributions to the digestion process have become increasingly apparent. However, the degree to which host and symbiont, and host enzymes, collaborate in lignocellulose digestion remain poorly understood. Also, how digestive enzymes specifically collaborate (i.e., in additive or synergistic ways) is largely unknown. In the present study we undertook translational-genomic studies to gain unprecedented insights into digestion by the lower termite Reticulitermes flavipes and its symbiotic gut flora. We used a combination of native gut tissue preparations and recombinant enzymes derived from the host gut transcriptome to identify synergistic collaborations between host and symbiont, and also among enzymes produced exclusively by the host termite. Our findings provide important new evidence of synergistic collaboration among enzymes in the release of fermentable monosaccharides from wood lignocellulose. These monosaccharides (glucose and pentoses) are highly relevant to 2nd-generation bioethanol production. We also show that, although significant digestion capabilities occur in host termite tissues, catalytic tradeoffs exist that apparently favor mutualism with symbiotic lignocellulose-digesting microbes. These findings contribute important new insights towards the development of termite-derived biofuel processing biotechnologies and shed new light on selective forces that likely favored symbiosis and, subsequently, group living in primitive termites and their cockroach ancestors.

Fifty years of attempted biological control of termites – Analysis of a failure

The use of pathogens as biological control agents has long been considered a promising technology for termite control. Over the past five decades, there has been a large accumulation of scientific literature on the development of control methods using various pathogens. However, despite the evidence that biological control has essentially failed, or failed to be developed, as a method for commercial termite control, this field of research remains very active. In this study, we examined 50years of research on the microbial control of termites in order to understand why commercial products have failed to be developed and why this field of research remains so active. All (to the extent of our knowledge) of the literature published between 1960 and 2011 was evaluated to investigate any publication bias and to detect false positives in the form of overly optimistic conclusions. This re-interpretation supports the idea that the conclusions frequently expressed have been misleading to some extent, or at least overly optimistic, about the potential for application of biological control to termites. Many results obtained from bioassays with poor biological relevancy have been interpreted as promising, while few results actually support practical application. We also suggest that the failure of termite biological control and the continued research emphasis in this area resulted in part from unrealistic optimism about the potential for development of environmentally friendly methods to control termites, publication bias, and poor understanding of termite biology.

Biology of Subterranean Termites: Insights from Molecular Studies ofReticulitermesandCoptotermes

Molecular genetic techniques have made contributions to studies on subterranean termites at all levels of biological organization. Most of this work has focused on Reticulitermes and Coptotermes, two ecologically and economically important genera. DNA sequence data have significantly improved our understanding of the systematics and taxonomy of these genera. Techniques of molecular biology have provided important new insights into the process of caste differentiation. Population genetic markers, primarily microsatellites, have furthered our understanding of the life history, population biology, community ecology, and invasion biology of subterranean termites. Recent results on the behavioral ecology of subterranean termites reveal a picture different from long-held views, especially those concerning colony breeding structures and foraging ranges. As additional molecular tools and genomic resources become available, and as more subterranean termite researchers incorporate molecular techniques into their approaches, we can expect accelerating advances in all aspects of the biology of this group.

Termite digestomes as sources for novel lignocellulases

AbstractFor most animals, lignocellulose is a nutritionally poor food source that is highly resistant to enteric degradation. Termites, however, have the unique ability to digest lignocellulose with high efficiency, often using it as a sole food source. Another interesting aspect of termite biology is their symbiotic associations with prokaryotic and eukaryotic gut symbionts. Termite symbionts contribute to lignocellulose digestion efficiency, but by no means are they responsible for 100% of lignocellulose digestion in the termite gut. The termite digestome can be defined as the pool of genes, both termite and symbiont, that contribute to lignocellulose depolymerization and digestion, as well as simple sugar fermentation, nutrient transport, and nutrient assimilation. A central goal of termite digestomics research is to define/understand the relative contributions of termite and symbiont gene products to collaborative lignocellulose digestion. While efficient microbial cellulases have already been identified and are presently being used in industrial applications, efficient and inexpensive pre‐treatments for lignin and hemicellulose depolymerization are not yet well developed. In this respect, termite digestomics has already offered significant insights, and can continue to identify relevant enzymes, as well as reveal how to optimally combine and utilize these enzymes for maximum synergy. The topics covered in this review are as follows: lignocellulose structure with emphasis on its potential for depolymerization by termite and gut endosymbiont‐derived digestive enzymes; termite biology and ecology from the perspectives of termite nutrition, gut physiology, and lignocellulose digestion; and trends identified through recent termite digestomics research. © 2008 Society of Chemical Industry and John Wiley & Sons, Ltd

Morphological aspects of Monocercomonas sp. and investigation on probable pseudocysts occurrence

Monocercomonas sp. is a flagellate protozoan found in the large intestine of snakes and in insects. Light microscopy revealed the measurements of morphological features of the trophozoites. Scanning electron microscopy showed in detail the emergence of the three anterior flagella, the recurrent flagellum, the axostyle, and the absence of undulating membrane. In addition, we described spherical forms which are probably pseudocysts. The investigation on the occurrence of this process was carried out through the incubation of Monocercomonas sp. trophozoites in several stressful conditions, such as pH change, nutrient depletion and different temperatures. Results revealed high pseudocyst formation at acidic pH values (4.0, 5.0, and 6.0), in absence of serum and in incubation at 37 degrees C. The occurrence of these pseudocystic forms in trichomonads life cycle is under investigation. This study describes the external structure of Monocercomonas sp., as demonstrated by light and scanning electron microscopy. Moreover, to our knowledge, this is the first time that formation of probable pseudocysts is shown in Monocercomonas sp., contributing to the research field on termite protozoa biology.

IPM for Drywood Termites (Isoptera: Kalotermitidae)1

The foundation of IPM for drywood termites (Isoptera: Kalotermitidae) has academic and industry origins some extending back several decades. Regardless of the origin, the underlying philosophy of IPM for drywood termites is consistent and includes correct identification of the pest, monitoring its activity, and use of a variety of treatment methods including chemical, nonchemical, and prevention. Species diversity and adaptive biology can make the detection and treatment of drywood termites challenging and difficult. Advances in detection technology now make it feasible to determine whether drywood termites are active within wood. Recent advances have also made it feasible to non-chemically treat for drywood termites. Efficacy testing is incomplete for many of the newer detection and treatment options especially field trials. In addition, pest control legislation and regulations have not kept up with the technological changes, particularly for detection devices and nonchemical treatment options. The interplay of drywood termite biology, detection, management options, and changes needed in public perception of termites and treatments are reviewed.

Caste- and development-associated gene expression in a lower termite.

Social insects such as termites express dramatic polyphenism (the occurrence of multiple forms in a species on the basis of differential gene expression) both in association with caste differentiation and between castes after differentiation. We have used cDNA macroarrays to compare gene expression between polyphenic castes and intermediary developmental stages of the termite Reticulitermes flavipes. We identified differentially expressed genes from nine ontogenic categories. Quantitative PCR was used to quantify precise differences in gene expression between castes and between intermediary developmental stages. We found worker and nymph-biased expression of transcripts encoding termite and endosymbiont cellulases; presoldier-biased expression of transcripts encoding the storage/hormone-binding protein vitellogenin; and soldier-biased expression of gene transcripts encoding two transcription/translation factors, two signal transduction factors and four cytoskeletal/muscle proteins. The two transcription/translation factors showed significant homology to the bicaudal and bric-a-brac developmental genes of Drosophila. Our results show differential expression of regulatory, structural and enzyme-coding genes in association with termite castes and their developmental precursor stages. They also provide the first glimpse into how insect endosymbiont cellulase gene expression can vary in association with the caste of a host. These findings shed light on molecular processes associated with termite biology, polyphenism, caste differentiation and development and highlight potentially interesting variations in developmental themes between termites, other insects, and higher animals.

A taxonomic index, with names of descriptive authorities of termite genera and species: an accompaniment to Biology of Termites: A Modern Synthesis (Bignell DE, Roisin Y, Lo N, Editors. 2011. Springer, Dordrecht. 576 pp.).

Biology of Termites: A Modern Synthesis (Bignell DE, Roisin Y, Lo N, (Editors), Springer, Dordrecht, 576pp, ISBN 978-90-481-3976-7, e-ISBN 978-90-481-3977-4, DOI 10.1007/978-90-481-3977-4) was published in 2011. With the agreement of the publishers, we give a taxonomic index of the book comprising 494 termite entries, 103 entries of other multicellular animal species mentioned as associates or predators of termites, with 9 fungal, 60 protist, and 64 prokaryote identities, which are listed as termite symbionts ( sensu stricto ). In addition, we add descriptive authorities for living (and some fossil) termite genera and species. Higher taxonomic groupings for termites are indicated by 25 code numbers. Microorganisms (prokaryotes, protists, and fungi) are listed separately, using broad modern taxonomic affiliations from the contemporary literature of bacteriology, protozoology, and mycology.

Sex pheromone identified after Solid Phase Microextraction from tergal glands of female alates in Cornitermes bequaerti (Isoptera, Nasutitermitinae)

For the first time, a termite sex pheromone secreted by tergal glands has been isolated and identified. In the mandibulate nasute termite Cornitermes bequaerti, pairing of swarming imagoes is mediated by a sex pheromone secreted by females from their tergal glands. These well developed sexual glands located in front of tergites 8, 9, 10 are essentially composed of class 1 and 2 cells, but also of some glandular units of class 3 cells. The major volatile compound of tergal secretion was isolated by solid phase microextraction (SPME) and identified by GC-MS as (3Z, 6Z, 8E)-dodecatrien-1-ol. Sex attraction bioassays with synthetic (3Z, 6Z, 8E)-dodecatrien-1-ol showed that this alcohol was the main component of the sex pheromone in C.bequaerti. The cellular origin and the key role of (3Z, 6Z, 8E)-dodecatrien-1-ol in the biology of termites are discussed.

Feeding groups, lifetypes and the global ecology of termites

Two termite functional classifications (Abe’s lifetypes and Donovan’s feeding groups) are evaluated, and then synthesized to make a single unified ‘lifeway’ matrix classification with eight categories. The systematics and biogeography of the lifeway groups are outlined. The lifeways are then tested against other relevant data on termite ecology (stable isotopes, molecular probes, survey data) to show that they consistently reflect real distinctions in termite biology. The advantages and disadvantages of each lifeway are discussed in the context of energy availability, nitrogen balance, foraging and nest‐building energetics, and biogeographical dispersal ability. Finally, an ecological evolutionary scheme is outlined for the global ecology of termites using the lifeway classification as a framework.

Subterranean termites in the urban landscape: Understanding their social structure is the key to successfully implementing population management using bait technology

Subterranean termites will likely continue to be major economic insect pests in the urban environment. Public concerns about pesticide use will not abate but continue to drive development and implementation of environmentally more acceptable control strategies for subterranean termites. Termite baits are a promising alternative to soil termiticide treatments for protection of structures, but the correlation between killing termites in the landscape and protecting structures is tenuous given our current understanding of termite biology. We discuss the problems associated with defining the efficacy of termite bait products in regard to determining termite population parameters in the field. This discussion is in the form of six case histories involving measures of termite activity and relatedness taken over a three-year period. Our findings highlight the need to include control populations in studies of termite bait efficacy, the mobility of termite populations over time, the importance of defining the techniques used to describe termite colony associations, and the need to use a multidisciplinary research approach in addressing the question of termite social structure.

Evaluation of Mark–Release–Recapture Methods for Estimating Forager Population Size of Subterranean Termite (Isoptera: Rhinotermitidae) Colonies

An evaluation of the application of mark–release–recapture models to assess foraging population sizes of subterranean termite colonies is presented. A combination of laboratory and field studies were used to examine the validity of 3 of the underlying assumptions, including persistence of dye marks (Nile Blue A), effect of dye mark on survivorship, and mix of marked and unmarked foragers within the interval between release and recapture in the eastern subterranean termites, Reticulitermes flavipes (Kollar), and R. virginicus (Banks). For both species, the percentage of individuals losing their dye marks when reared on a mixed wood diet was significantly higher than for termites reared on a filter paper diet for 27 d after marking (both treatments permitting limited exercise). There were considerable differences in dye loss between colonies within species. Mortality differences among dyed and undyed termites, although statistically significant, were relatively small and probably do not affect population size estimates derived from mark–release–recapture models. The movement of marked termites between equivalent food resources is unpredictable and contrary to the model assumption of marked termites fully mixing within the population within the interval between recaptures. A simulation is presented to investigate how variables such as dye loss, mortality, and probability of recapture affect accuracy of colony size estimates and their standard errors. The number of recaptures is a dominant factor driving the accuracy of the population estimates generated from these models, but the number of marked termites recaptured in proportion to population size is impossible to assess in field colonies because we do not know the true population size of the foraging colony. Data suggest that validity of mark–release–recapture results may be compromised by the fact that aspects of the biology of subterranean termites violate critical assumptions of the models. Forager population estimates generated by mark–release–recapture studies of subterranean termite colonies must therefore be interpreted with caution.

Mark–Release–Recapture Estimates of Reticulitermes spp. (Isoptera: Rhinotermitidae) Colony Foraging Populations from Georgia, U.S.A.

Three subterranean termite species [eastern subterranean termite, Reticulitermes flavipes (Kollar); R. virginicus (Banks); and R. hageni (Banks)] were included in 67 mark–release–recapture experiments conducted with 57 different colonies in Georgia over 3 yr (1992, 1993, and 1995). Data were collected in 1992–1993 under a triple-mark–release protocol and analyzed using 2 mathematical models–the Lincoln index and a weighted mean model. During 1995, data were collected using a single release of marked termites followed by 3 collections and analyzed using the Lincoln index. In addition, 71 different termite infested logs were returned to the laboratory where termites were extracted and counted. Termite foraging population estimates ranged from 106 to 1,453,021 for the weighted mean model and 127 to 384,617 for the Lincoln index in 1992–1993. The 1995 Lincoln index estimates ranged from 1,463 to 3,547,152 termites per colony. The numbers of termites extracted from infested logs ranged from 1,033 to 344,457 termites per log. Both mathematical models applied to the 1992–1993 data provided similar population estimates. The 1995 Lincoln index data provided population estimates which were higher than the 1992–1993 data, median 98,202 and 28,473 termites per colony, respectively. Results of these mark–release–recapture experiments, when examined by capture cycle, suggest that the biology of subterranean termites may violate some of the assumptions of these mathematical models for estimating population size.